Electronics International CA-1 - Manual (Page 9)

Operating Information
6
EGT's
engines tend to operate smoother at 25‘F on the rich side of peak EGT. Fuel-injected engines will provide a
more precise peak. Most engines normally operate within an EGT range of 1300‘F to 1600‘F at cruise
power.
Some engine manufacturers allow leaning to peak EGT at 75% power and below on their direct drive nor-
mally aspirated engines. For your engine, check the engine manufacturer’s recommended procedures. It
is not recommended to lean to peak EGT above 75% power settings. The richer mixture is needed to cool
the combustion temperatures and keep the anti-knock capability of the fuel high enough to prevent detonation
from occurring at the higher power settings.
2. EGT Diagnostics:
Since the EGT is directly related to the combustion temperature, it is an indication of the engine’s ability to
produce power. If the engine is not producing the correct amount of power, the EGT instrument can be a
very valuable troubleshooting tool as well an early warning system before engine failure occurs. With 1‘F
resolution, our digital EGT instruments will react to the slightest changes in the combustion process. To
detect a problem, become familiar with your engine’s normal EGT readings during run-up, climb, cruise and
descent. Any difference from the norm can be a sign of trouble.
During normal operation the EGT will stabilize to 1‘F for a given throttle and mixture setting. If it does not
stabilize, this can also be the first sign of trouble. With rate and trend information being displayed instanta-
neously and with temperatures being read to 1‘F, few problems can escape the pilot flying one of Electronics
International’s analyzer systems. The following is a list of EGT/CHT symptoms and possible problems:
Symptom Possible Problem
One EGT reads abnormally high. The correspond-
ing CHT reads lower than normal.
Burned valve or broken ring, defective plug, plug
wire or mag.
One EGT reads abnormally high. The correspond-
ing CHT reads higher than normal.
Plugged injector, intake leak.
One EGT reads abnormally low. Over-sized injector, restricted exhaust, broken or
leaky exhaust header.
High CHT’s and/or high EGT’s on all cylinders. Excessive leaning with power settings over 75%.
Detonation due to bad fuel. Closed or restricted
cowl flaps. Missing or loose baffling.
Timing problem or defective mag.
Jumpy readings on one channel.
High EGT’s and/or low CHT’s on all channels.
This is not an engine problem. Check all connec-
tions and the probe for proper operation. See
Troubleshooting Section of this manual.